Method and apparatus for automatically cleaning syringes

ABSTRACT

A SEALED CHAMBER IS PLACED ON THE PLUNGER END OF AN OTHERWISE CONVENTIONAL SYRINGE. THE PLUNGER IS AUTOMATICALLY MOVED AXIALLY THROUGH THE SEALED CHAMBER. A WASH SOLVENT IS INTRODUCED IN THE CHAMBER SUCH THAT AS THE PLUNGER IS WITHDRAWN FROM THE SYRINGE, THE PLUNGER IS CLEANED BY THE SOLVENT. NEXT A DRYING GAS IS INTRODUCED INTO THE CHAMBER TO FORCE THE WASH SOLVENT DOWN THROUGH THE SYRINGE, THEREBY CLEANING THE SYRINGE AND THE SYRINGE NEEDLE WITH THE WASH SOLVENT. THE PLUNGER IS REINSERTED IN THE SYRINGE AND THE SYRINGE IS READY FOR RELOADING.

19 s. E. LIGHTNER ETAL 3,577,279 '.METHOD AND APPARATUS FOR AUTOMATICALLY CLEANING SYRINGES. Filed'Novr as, 1968 2 sheets-sheet 1' ATTORNEYS May 4, 1971 G. E. LIGHTNER ETAL 3,577,219

METHOD AND APPARATUS FOR AUTOMATICALLY CLEANING SYRINGES Filed Nov. 26, 1968 Y z Sheets-Sheet 2 INVENTORS r H. Blair sbsiw Louis E. Green BYWMW ATTORNEYS United States Patent Calif.

Filed Nov. 26, 1968, Ser. N0. 779,019 Int. Cl. B08b 9/00 US. Cl. 134-23 13 Claims ABSTRACT OF THE DISCLOSURE A sealed chamber is placed on the plunger end of an otherwise conventional syringe. The plunger is automatically moved axially through the sealed chamber. A wash solvent is introduced in the chamber such that as the plunger is withdrawn from the syringe, the plunger is cleaned by the solvent. Next a drying gas is introduced into the chamber to force the wash solvent down through the syringe, thereby cleaning the syringe and the syringe needle with the wash solvent. The plunger is reinserted in the syringe and the syringe is ready for reloading.

BACKGROUND OF THE INVENTION This invention relates to a method and apparatus for cleaning a sampling syringe automatically.

Many analytical instruments accept liquid samples often in minute quantities, for analysis. Precision fluid syringes are typically used for this purpose. Among the precision syringes that are available today, many are capable of accurately handling samples of one-tenth of a microliter and less. When using these precision syringes, particularly with the extremely sensitive analytical instruments such as a gas chromatograph, which are available to the chemist of today, great care must be exercised in insuring the syringe is thoroughly cleaned before the sample under test is selected. Because of the minute quantities and the possibility of cross contamination between samples, accurate and repeatable analyses are a real problem.

Typically, the analyst cleans his syringe by dipping the syringe needle in a wash solvent and pumping the syringe plunger back and forth to insure that the syringe barrel and needle are thoroughly clean. To be thorough, the chemist removes the plunger entirely, rinses it, and draws a solvent through the syringe barrel and needle by application of a vacuum. If he Wishes to be even more precise, he will then force a drying gas, which may be heated if desired, under pressure through the syringe barrel and needle, thereby to insure that the syringe is completely 'dry prior to using it for another sample. All of these procedures, while quite satisfactory, are quite time consuming and somewhat tedious.

With the advent of the computer and associated automatic sampling systems, wherein the operation of the syringe itself is completely automated, cleaning of the syattaching a side vent to the syringe immediately adjacent the syringe needle. The plunger is partially withdrawn and 'a wash solvent passed through the side vent and needle thereby to flush the needle of contamination. The syringe is then ready for usage. While an improvement over other syringes available in the prior art, this syringe still does not solve the problem of contamination or residue on the 3,577,279 Patented May 4, 1971 plunger or the problem of cleaning the entire syringe out and drying the same so that there is no dilution or contamination of subsequent samples.

It is, therefore, an object of this invention to obviate many of the disadvantages of prior art syringes, particularly those that are adapted for use in automatic sampling systems.

Another object of this invention is to provide an improved method of automatically cleaning syringes.

Still another object of this invention is to provide an improved apparatus for automatically cleaning syringes.

BRIEF DESCRIPTION OF THE INVENTION A preferred method of cleaning a syringe automatically in accordance with this invention includes the steps of passing a wash solvent into a sealed chamber which encloses the plunger end of the syringe barrel and withdrawing the plunger from the syringe through the wash solvent thereby cleaning the plunger. The wash solvent is permitted to flow down through the syringe itself, cleaning the syringe and the syringe needle. Next in the sequence, the wash solvent is cut off and a drying gas passed through the chamber and the syringe to dry the entire system including the syringe. The plunger is reintroduced into the syringe and is ready for a subsequent sample.

A preferred apparatus for performing this method includes a sealed chamber which encloses the 'plunger end of the syringe and provides a sealing gland and plunger guide through which the plunger moves. A source of pressurized wash solvent and a source of drying gas are then connected through valves and a conduit to the sealed chamber such that the wash solvent and/ or gas may be selectively introduced into the cleaning chamber as desired. The valves may be selectively operated under the control of a programmer to automate the entire operation.

BRIEF DESCRIPTION OF THE DRAWINGS The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will be best understood from the following description, given for illustrative purposes only, when read in connection with the accompanying drawings, in which:

FIG. 1 is a pictorial view of a fluid syringe having a sealed wash chamber constructed in accordance with a preferred embodiment of this invention;

FIG. 2 is a cross-sectional view of the wash chamber illustrated in FIG. 1 taken along the section lines 22;

FIG. 3 is a schematic diagram of an automatic syringe cleaning system including a syringe positioned in a washchamber, the syringe being connected to be operated automatically under the control of a programmer to perform the wash and dry cycles of the syringe;

FIG. 4 is a partial schematic diagram of the automatic syringe cleaning system of FIG. 3 in one of the steps of its operational sequence;

FIG. 5 is a partial schematic diagram of the automatic syringe cleaning system illustrated in FIG. 3 in a subsequent step of its automated operation;

FIG. 6 is a partial schematic diagram of the automatic syringe cleaning system illustrated in FIG. 3 in a still later step of its automated operation during which drying gas is passed through the syringe;

FIG. 7 is a cross-sectional view of an alternative embodiment of the syringe washing chamber illustrated in FIG. 1;

FIG. 8 is a cross-sectional view of still another embodiment of the syringe washing chamber illustrated in FIG. 1; and

FIG. 9 is a cross-sectional view, partially shown in schematic form, of still another embodiment of the syringe washing chamber illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIG. 1, a preferred embodiment of the invention includes a wash chamber housing 10 which sealingly encloses the plunger end of a conventional liquid syringe 12. The syringe 12 includes a barrel 14, needle 16, plunger 18 and finger button 20 on the end of the plunger. The housing 10 has secured thereto, as by brazing or soldering, a plunger guide 22. The plunger guide 22 includes a pair of axially disposed guide rods or members 24 upon which a slider 26 is adapted to slide. The slider 26 engages both of the upright members 24 and is in the form of a U-shaped member having an orifice (not shown) in the bottom of the U through which the plunger 18 may slide. Springs 28 are coiled about the guide members 24 to insure that the slider 26 returns as the plunger 18 is withdrawn from the syringe, to some middle position along the guide members 24 so as to ride typically halfway up the extended length of the plunger shaft. In the drawing, the plunger is illustrated in a depressed position.

When the syringe is employed in an automatic system, the plunger guide is particularly useful. In such system, the plunger 18 is depressed quickly and automatically by pneumatic cylinders or other actuating means. The rapid application of force to the plunger sometimes causes the plunger to bend. The purpose of the plunger guide 22 is to guide the plunger 18 and prevent its bending during the time it is being depressed. A pair of nuts or other retaining members 32 prevent the slider 26 from leaving the guide members 24.

The particular manner by which the plunger is moved does not form part of this invention. But, by way of making a full and complete disclosure, there is illustrated in FIG. 3 a prime mover, denoted by the block 34, conneected through a suitable mechanical linkage, denoted by the dashed line 36, to the finger button 20. This linkage 36 may, for example, be the piston of a pneumatic cylinder which is secured to the end of the finger button 20 of the plunger 18 as by a clip or other suitable mechanism (not shown). An automatic syringe actuating system with which this automatic syringe cleaning apparatus finds use is shown and claimed, for example, in a patent application entitled Automatic Liquid Sampler, filed Sept. 18, 1968 and bearing the Ser. No. 760,538 now Patent No. 3,508,- 442, issued Apr. 28, 1970 and assigned to the same assignee as the present application.

The wash chamber housing 10 has several different embodiments. One embodiment is that illustrated in FIG. 2 which shows the housing in cross-section. The housing 10 includes a generally cylindrical member '40 having a central axial bore 42 which is adapted to accommodate the plunger 18. The bore has a diameter greater than the diameter of the plunger 18 so that the plunger may slide freely along its axis therethrough and yet be guided by the bore 42. The bore 42 in turn is counterbored to form a septum retaining bore 44 in which is disposed a conventional septum 46. The septum may be made of rubber or other suitable material typically used to form a septum. Such material should be capable of being punctured by the plunger 18 and yet maintain a sealing engagement with the plunger to prevent fluid leakage about the plunger. Next a septum retaining member or spacer 48 is disposed in the bore. The spacer 48 is generally in the form of a. hollow cylinder having an end flange 50 which engages the side walls of the septum bore 44 and provides an annular space 52 within the bore 44. A radial bore 56, to which a conduit or tube 58 may be connected to supply wash solvents or drying gases, as will be described in conjunction with FIG. 3, is formed in the side wall of the housing 10 to communicate with the annular space 52.

The spacer member 48 has radial orifices 59 therein which permit the fluids or gases supplied through the tube 58 to be supplied to the central region 62 which provides the washing chamber of the spacer 48. The septum spacer 48 has a restricted portion having an orifice 49 of slightly greater diameter than the plunger 18 to again serve as a guide for the axial movement of the plunger to insure that the plunger is in proper alignment with the syringe barrel 14. Both the top end (in the drawing) of the bore 42 and the orifice 49' are flared to facilitate introducing the plunger through the septum 46 and into the syringe barrel.

To complete the cylindrical member 40, a second counterbore 64 is formed therein and is threaded. This second counterbore is adapted to accommodate the plunger end of the syringe barrel 14, which is illustrated as being flanged at 66 since most syringes have a finger flange 66 although such flange is not necessary for the proper functioning of this invention. A sealing washer 68 is positioned between the flange 66 or upper end of the syringe and the end of the second bore 64 to provide a seal and complete the formation of the sealed washing chamber 62. The sealing washer 68 engages the lower end of the septum spacer 48. Finally, a pair of O-rings 70 are placed in the second counterbore and positioned on either side of the finger flange 66 to aid in the positioning and sealing of the upper end of the syringe. This insures that the wash chamber 62 is completely sealed about the upper end of the syringe. The septum sealingly encloses the plunger 18. An externally threaded annular sealing plug fits over the syringe barrel 14 and engages the threaded bore 64 to retain the O-rings 70 and flanged barrel 14 in position. Tightening the plug 110 enables the O-rings to maintain an appropriate seal about the finger flange 66.

In this manner, if a wash solvent is introduced through the tube 58 into the wash chamber 62 and the plunger 18 then withdrawn from the syringe, it is seen that the entire length of the plunger 18 must pass through the wash chamber 62 and thereby be exposed to rinsing by the wash sol-vent. This has the beneficial eifect of cleaning the entire periphery of the plunger and removing any residues which may be deposited thereon. Once the plunger 18 is completely withdrawn from the syringe, the wash solvent is free to flow down through the axial barrel chamber of the syringe 14 and through the syringe needle 16 thus cleansing these elements of any contaminating and other unwanted residues. As a final step, the flow of wash solvent, which is typically applied under pressure due to the high flow resistance imposed by the small volume of the syringe barrel chamber and needle, may be cutoff and a drying gas applied through the line 58 to the wash chamber 62. This drying gas passing through the interior of the syringe 14 and needle 16 forces the remainder of the wash solvent through the wash chamber 62 and syringe and dries out the wash chamber and syringe. The plunger '-18 may then be reintroduced into the syringe and the syringe is completely clean and ready for a subsequent sample. This cleansing and drying operation may be repeated several times as desired. Alternatively, the drying gas flow may be omitted or used in place of the wash solvent at the option of the user.

A system for automating this syringe Washing and/or drying operation is illustrated in FIG. 3. As may be seen in FIG. 3, the syringe 12 is enclosed in the sealed wash chamber housing 10 which is illustrated only diagrammatically as having the wash chamber 62 with the tube or conduit 58 communicating therewith. The plunger 18 passes through the wash chamber and is connected by a mechanical linkage, as denoted by the dashed line 36, to be moved along its axis back and forth by the prime mover 34. The prime mover 34, which may be a pneumatic cylinder or other suitable actuating mechanism, is controlled by a conventional program controller 80. The program controller may, for example, be the Output of a digital computer or may be simply the output of a punched tape reader or other suitable control mechanisrrnWhatever the program controller employed, it passes signals to the prime mover 34 to displace the syringe plunger '18. The program controller 80 also is connected to control a second prime mover, denoted by the block 82.

The second prime mover 82 may be a three position solenoid or servo motor, by way of example, and is connected by a suitable mechanical linkage illustrated by the dashed line 83 to position a rotary valve 84. The rotary valve 84 may be of known type which is available commercially and may have a central orifice 86 which is continually connected to the conduit of tube 58. The tube 58 is selectively connected by the valve 84 to any one of three inlet valve ports 88 and 90 and 92. The first port 88 which preferably is the neutral position of the valve 84, is connected to atmosphere or vent. The second port 90 is connected through a suitable conduit to a solvent supply chamber illustrated by the block 94. The solvent may be any suitable wash solvent such as acetone, hexane, chloroform, water, alcohol, etc. which is capable of cleaning the residue or other contaminants from the syringes. The solvent typically is held under suitable pressure so that it is capable of easily flushing the syringe chamber 62. Finally, the third port 92 is connected through a suitable conduit to a source of a drying gas illustrated by the block 96. The drying gas may be any suitable gas such as air, also maintained under pressure.

Under the influence of the program controller 80, the syringe plunger 18 initially is in its in position as illustrated in FIG. 3. The second prime mover 82 is energized by the program controller 80 to position the three way valve 84 to connect the second port 90 and hence wash solvent to the conduit 58, thereby filling the Wash chamber 62 as is illustrated in FIG. 4. As the plunger 18 is withdrawn, it is subjected to and continuously immersed in the wash solvent which removes undesired residues therefrom.

As the next step in the sequence, the plunger 18 is completely withdrawn from the syringe barrel by the prime mover 34, as illustrated in FIG. 5. The wash solvent in the wash chamber 62 thereby is forced through the barrel chamber 100 and needle 16 cleaning each thoroughly. After 0.2 to 0.5 milliliters of the wash solvent has flowed through the syringe (this is typically the quantity utilized in a microliter syringe for washing with twenty volumes of solvent) the three-way valve 84 is rotated by the second prime mover 82 to connect the third port 92 with the conduit 58 as is seen in FIG. 6. This permits a drying gas to force the wash solvent out of the wash chamber 62 and through the barrel chamber 100 and needle 16. The Wash solvent is immediately followed by the fiow of drying gas which blows the liquid from the barrel and needle and thoroughly dries the several elements. As a final step, the first prime mover 34 repositions the plunger 18 into the syringe chamber 100. This operation is facilitated by the guiding action of the orifice 42 in the housing and the restricted portion 49 of the septum spacer 48. This is particularly facilitated by the flared end opening of the syringe barrel which typically is designed into the syringe itself. This sequence of operations, particularly when the syringe is employed in an automatic sampling system of the type hereinbefore described, may be repeated several times if desired. The order may be modified such that the drying gas is passed first if desired. Furthermore, the order may be modified such that any sequence or combination of sequences of solvent and drying gas is available if desired.

There are several other embodiments of the wash chamber housing 10. Thus in the embodiment of FIG. 7, the housing 10 includes a bore 42 adapted to accommodate the plunger 18. The bore 42 is counterbored from each end. The lower end (in the drawing) forms the wash chamber 62; the upper end a pressure chamber 114. The syringe barrel 14 is seated within a second counterbore 64 formed in the lower counterbore in much the same manner as previously described, thecounterbore being threaded and having a coaxially disposed, annular plug member which fits into the counterbore 64 to compress the O-rings 70 and provide a seal about the finger flange 66. At this point the similarity between the embodiments of FIGS. 2 and 7 ends. In FIG. 7 thesealing washer 68 and spacer need not be used. Instead, the wash chamber 62 is smaller in size and has the radial orifice 56 communicating directly therewith. In addition, a sec: ond radial bore 112'is formed in the housing 10'to communicate with the pressure chamber 114. The outside end of the pressure chamber 114 is slightly swaged at 115v to aid in guiding the plunger 18 and forming a restriction which prevents the ready escape of gas. Air is supplied through the radial bore 112 to the pressure chamber 114 of suitable pressure to equalize that of the solvent pressure supplied to the wash chamber 62. Since the pressure on either side of the bore 42 is approximately equal, there is in effect a seal and little leakage occurs through the restriction. The embodiment of FIG. 7 is seen to provide an air seal for the wash chamber 62. v

Still another embodiment is illustrated in FIG. 8 which is quite similar to and has many of the same parts as the embodiment shown in FIG. 7, the primary difference being that a third counterbore is formed in the upper end (in the drawing) of the housing chamber 10. This third counterbore accommodates a packing 122 having a central axial bore therein to accommodate the plunger 18. An annular packing retaining nut 124 is inserted about the plunger 18 to compress the packing 122 and provide the desired seal about the plunger. The packing 122 may be any suitable plastic material which is relatively inert to avoid contamination of the plunger and somewhat resilient to provide the desired seal. Suitable materials of this type are polytetrafluoroethylene which is sold under the trademark Teflon or polyamide which is sold under the trademark nylon.

Still another embodiment of this invention is that illustrated in FIG. 9 which is constructed in substantially the same manner as the embodiment illustrated in FIG. 8. The only difference between the two is that in the embodiment of FIG. 9 the syringe barrel14 is illustrated as having no finger grip flange as flange 66 in the earlier embodiments. Actually the flange is preferred even with .this embodiment. This permits a single O-ring 132 to provide the desired seal. The wash chamber 62 has a second radial bore 134 communicating therewith and connected through a valve 136 to atmosphere or vent. This connection is made to relieve the air pressure which is sometimes encountered when the wash solvent is initially introduced into the wash chamber 62 prior to the time that the plunger 18 is withdrawn therefrom. This is of no general problem since the air present in the wash chamber 62 is compressed by the introduction of the wash solvent and normally rises to the top of the wash chamber 62 and causes no further problems. In the event, however, that the syringe is in a normally horizontal position for cleaning, this bubble sometimes can be troublesome. In these instances the vent bore 134 is necessary and desirable to relieve the air pressure and is closed by a prime mover 138 acting through a linkage 140 immediately after the wash solvent fills the wash chamber 62. The prime mover may be controlled by the program controller 80. In some applications it may be desirable to flush the Wash solvent through the wash chamber 62 during the time the plunger is being withdrawn. This embodiment has application for this usage also.

There has thus been described a method and apparatus for cleaning a syringe. The method involves relatively simple steps and permits the entire plunger as well as the interior of the syringe barrel and syringe needle to be thoroughly cleaned and/ or dried either manually or automatically with greater facility than has been available heretobefore.

While the invention has been disclosed herein in connection with certain embodiments and certain structural and procedural details, it is clear that changes, modifications or equivalents can be used by those skilled in the art; accordingly, such changes Within the principles of the invention are intended to be included within the scope of the claims.

What is claimed is:

1. A method of cleaning a syringe having a plunger, barrel chamber to receive said plunger, and needle comprising the steps of:

passing a wash solvent into a sealed chamber enclosing the plunger end of said barrel and withdrawing said plunger from said barrel through said chamber and hence said wash solvent, thereby to clean said exposed said plunger shaft as it passes through said sealed chamber.

2. A method according to claim 1 wherein said plunger is withdrawn from said barrel chamber, thereby to wash said plunger shaft and pass said wash solvent through said syringe.

3. A method according to claim 2 which includes the additional step of passing a drying gas through said sealed chamber and said barrel chamber to drive said wash solvent therefrom and dry said chambers.

4. A method according to claim 3 which includes the additional step of reinserting said plunger into said barrel chamber.

5. Apparatus for cleaning a syringe having a plunger, needle and barrel chamber comprising:

a sealed cleaning chamber enclosing the plunger end of said barrel chamber,

said cleaning chamber having an orifice adapted to permit axial movement of said plunger relative to said syringe barrel chamber,

sealing means associated with said orifice to seal said chamber against fluid leakage around said plunger, and

conduit means for introducing a fluid into said cleaning chamber, thereby to clean said plunger and barrel chamber.

6. An apparatus according to claim 5 wherein said sealing means includes a septum.

7. An apparatus according to claim 5 wherein said sealing means includes a plastic, resilient packing.

8. An apparatus according to claim 5 which also includes a bore coaxially disposed about said plunger adjacent said cleaning chamber, said bore having a restriction defining said cleaning chamber and a second chamber, and means for introducing gas into said second chamber under pressure suflicient to equalize the pressure across said restriction between said chambers, thereby to elfectively seal said cleaning chamber.

9. An apparatus according to claim 5 which also includes:

second conduit means communicating with said cleaning chamber thereby to provide a vent for said chamber, and

valving means adapted to close said second conduit means.

10. An apparatus according to claim 5 which also includes means connected to said conduit means for passing a drying gas into said cleaning chamber.

11. An apparatus according to claim 10 which also includes means connected to said conduit means for passing a wash solvent into said cleaning chamber.

12. An apparatus according to claim 11 which also includes first actuating means for withdrawing said plunger from said syringe barrel chamber through said sealed chamber, thereby permitting the flow of said solvent and said gas through said syringe barrel and needle.

13. An apparatus according to claim 12 which also includes valving means in said conduit means for controlling the passage of said solvent and gas through said conduit means, second actuating means for operating said valving means, and programming means for selectively energizing each of said actuating means to pass solvent into said chamber, Withdraw said plunger, flush said barrel chamber with said solvent, dry and cleaning and barrel chamber and reintroduce said plunger into said syringe.

References Cited UNITED STATES PATENTS 2,843,508 7/1958 Sheft 134-22 JOSEPH SCOVRONEK, Primary Examiner D. G. MILLMAN, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,577,279 Dated May 4, 1971 Inventor) Gene E. Lightner et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 line 59 "uncleand" should read uncleaned f Column 8 line 35 "dry and cleaning" should read dry said cleaning Signed and sealed this 21st day of September 1971.

(SEAL) Attest:

EDWARD M. FLETCHERJR. ROBERT GOTTSCIIALK Attesting Officer Acting Commissioner of Patents FORM PC4050 (O-69 LJSCOMM-DC wave-pen U S GOVERNMENY PHINHNG OFFICE 1969 O Jbb-AJ-l 

